Consumers continue to demand faster computers. Multithreading technology, such as Simultaneous Multi-Threading (SMT), is an effective way to boost throughput performance with limited impact on a processor die area. SMT increases processor throughput by executing a plurality of processing threads in parallel. However many software applications do not benefit from SMT because they are single threaded and, therefore, do not take advantage of the multithreading technology.
In addition, the gap between processor and memory speed continues to widen, with processor speed exceeding memory speed. As a result, computer performance is increasingly determined by the effectiveness of processor cache hierarchy. Prefetching, which is a process by which instructions are transferred from system memory to cache memory, is a well known and effective technique for improving the effectiveness of the cache hierarchy. However, prefetching alone may not guarantee that a software application will be able to benefit from the speed of the cache memory. In addition, some effort is needed to prevent the prefetched variable from being removed from the cache before the software application has been able to use the prefetched variable.